The present invention relates to a catalyst system suitable for polymerizing unsaturated monomers and comprising active constituents obtainable by reacting
A) a transition metal compound with
B) aluminum trifluoride,
C) a cation-forming compound and, if desired,
D) further components.
The present invention also relates to the use of aluminum trifluoride as activator in a catalyst system, to a process for preparing a catalyst system, to a process for preparing polymers based on monomers having Cxe2x80x94C double bond and/or Cxe2x80x94C triple bond, and to the use of a catalyst system for forming carbon-carbon covalent bonds or carbon-heteroatom covalent bonds.
It is known that the following reactions, for example, can be performed in preparing metal compounds that are active in polymerization, such as metallocenium ion catalysts:
a) metallocenedialkyl+strong cation-forming compound (Lewis acid), X. Yang, C. L. Stern. T. F. Marks, J. Am. Chem. Soc. 1991, 113, 3623-5
b) metallocenedialkyl+Brxc3x6nsted acid with non-nucleophilic anion, EP 0 591 756 (Idemitsu Kosan)
c) metallocene compound+aluminoxane EP 0 035 242 (BASF AG)
Reactions a) and b) have the common feature that they are severely restricted in terms of the choice of activator; that is, of the strong cation-forming compound and of the Brxc3x6nsted acid with non-nucleophilic anion. Only very specific, preferably perfluoroaromatic, boron compounds lead to a usable activator. Reaction c) requires large amounts of expensive aluminoxane, which is a disruptive factor in the resulting polymer.
There is therefore a desire to prepare active catalysts based on inexpensive, readily available and widely applicable activators. R. Taube in DD 265 150 A1 describes the polymerization of 1,3-butadiene in the presence of a mixture of nickel cyclodecatriene or nickel acetylacetonate with aluminum triethyl and aluminum trifluoride. The polymerization of other monomers, especially alkenes or styrene and its derivatives, and other catalysts, comprising aluminum trifluoride plus a cation-forming compound, are not mentioned.
It is an object of the present invention to provide a catalyst system which is not severely restricted in terms of the choice of activator. This means that even customary cation-forming compounds commonly employed in preparative organic chemistry, such as hexafluoroantimonic acid HSbF6, antimony pentafluoride SbF5, and trifluoromethanesulfonic acid CF3SO3H, could be used to generate transition metal catalysts. In addition, the catalyst system ought to be able to function per se as a supported catalyst or to be convertible to such a catalyst.
We have found that this object is achieved by the catalyst system defined at the outset, by the use of aluminum trifluoride in the catalyst system defined at the outset, by a process for preparing the catalyst system defined at the outset, by a process for preparing polymers using the catalyst system defined at the outset, and by the use of the catalyst system defined at the outset for forming carbon-carbon covalent bonds or carbon-heteroatom covalent bonds.
Suitable transition metal compounds A) are in principle all those which react with components B), C) and, if used, D) chemically to form an active catalyst.
Examples of highly suitable transition metal compounds A) are transition metal complexes with a ligand of the formulae F-I to F-IV 
where the transition metal is selected from the elements Ti, Zr, Hf, Sc, V, Nb, Ta, Cr, Mo, W, Fe, CO, Ni, Pd and Pt or from an element of the rare earth metals. Preference is given here to compounds of nickel and palladium as the central metal.
E is an element from group 15 of the Periodic Table of the Elements (5th main group), preferably N or P and, with particular preference, N. The two atoms E in a molecule can be the same or different.
The radicals R1A to R18A, which can be the same or different, are as follows:
R1A and R4A are independently of one another hydrocarbon radicals or substituted hydrocarbon radicals, preferably those where the carbon adjacent to the element E is attached to at least two carbon atoms.
R2A and R3A are independently of one another hydrogen, hydrocarbon or substituted hydrocarbon radicals or else together form a ring system which may also include one or more heteroatoms.
R6A is hydrocarbon or substituted hydrocarbon radicals,
R5A is hydrogen, hydrocarbon or substituted hydrocarbon radicals,
R6A and R5A may also together form a ring system.
R8A is hydrocarbon or substituted hydrocarbon radicals,
R9A is hydrogen, hydrocarbon or substituted hydrocarbon radicals,
R8A and R9A may also together form a ring system.
R7A each independently of the others is hydrogen, hydrocarbon or substituted hydrocarbon radicals, it also being possible for two radicals R7A to form a ring system. n is an integer between 1 and 4, preferably 2 or 3.
R10A and R14A independently of one another are hydrogen, hydrocarbon or substituted hydrocarbon radicals.
R11A, R12A and R13A independently of one another are hydrogen, hydrocarbon or substituted hydrocarbon radicals, where two or more radicals R11A, R12A and R13A may also together form a ring system.
R15A and R18A independently of one another are hydrogen, hydrocarbon or substituted hydrocarbon radicals.
R16A and R17A independently of one another are hydrogen, hydrocarbon or substituted hydrocarbon radicals.
Examples of particularly suitable compounds F-I to F-IV are:
Di(2,6-di-i-propylphenyl)-2,3-dimethyldiazabutadienepalladium dichloride Di(di-i-propylphenyl)-2,3-dimethyldiazabutadienenickel dichloride Di(2,6-di-i-propylphenyl)-dimethyldiazabutadienepalladium dimethyl Di(2,6-di-i-propylphenyl)-2,3-dimethyldiazabutadienenickel dimethyl Di(2,6-dimethylphenyl)-2,3-dimethyldiazabutadienepalladium dichloride Di(2,6-dimethylphenyl)-2,3-dimethyldiazabutadienenickel dichloride Di(2,6-dimethylphenyl)-2,3-dimethyldiazabutadienepalladium dimethyl Di(2,6-dimethylphenyl)-2,3-dimethyldiazabutadienenickel dimethyl Di(2-methylphenyl)-2,3-dimethyldiazabutadienepalladium dichloride Di(2-methylphenyl)-2,3-dimethyldiazabutadienenickel dichloride Di(2-methylphenyl)-2,3-dimethyldiazabutadienepalladium dimethyl Di(2-methylphenyl)-2,3-dimethyldiazabutadienenickel dimethyl Diphenyl-2,3-dimethyl-diazabutadienepalladium dichloride Diphenyl-2,3-dimethyl-diazabutadienenickel dichloride Diphenyl-2,3-dimethyl-diazabutadienepalladium dimethyl Diphenyl-2,3-dimethyl-diazabutadienenickel dimethyl Di(2,6-dimethylphenyl)-azanaphthenepalladium dichloride Di(2,6-dimethylphenyl)-azanaphthenenickel dichloride Di(2,6-dimethylphenyl)-azanaphthenepalladium dimethyl Di(2,6-dimethylphenyl)-azanaphthenenickel dimethyl 1,1xe2x80x2-Dipyridylpalladium dichloride 1,1xe2x80x2-Dipyridylnickel dichloride 1,1xe2x80x2-Dipyridylpalladium dimethyl 1,1xe2x80x2-Dipyridylnickel dimethyl
Further particularly suitable transition metal compounds A) are those having at least one cyclopentadienyl-type ligand, which are commonly known as metallocene complexes (two or more cyclopentadienyl-type ligands) or half-sandwich complexes (one cyclopentadienyl-type ligand).
Particularly suitable metallocene complexes are those of the formula 
where
M is titanium, zirconium, hafnium, vanadium, niobium or tantalum or an element from subgroup III of the Periodic Table or from the lanthanoids,
X is fluorine, chlorine, bromine, iodine, hydrogen, C1-C10-alkyl, C6-C15-aryl, alkylaryl having 1 to 10 carbons in the alkyl radical and 6 to 20 carbons in the aryl radical, xe2x80x94OR6 or xe2x80x94NR6R7,
n is an integer between 1 and 3, n corresponding to the valence of M minus 2,
and where
R6 and R7 are C1-C10-alkyl, C6-C15-aryl, alkylaryl, arylalkyl, fluoroalkyl or fluoroaryl having in each case 1 to 10 carbons in the alkyl radical and 6 to 20 carbons in the aryl radical,
R1 to R5 are hydrogen, C1-C10-alkyl, 5-7 membered cycloalkyl which can in turn carry a C1-C10-alkyl as substituent, C6-C15-aryl or arylalkyl, where two adjacent radicals may if desired together be saturated or unsaturated cyclic groups having 4 to 15 carbons, or are Si(R8)3 where
R8 is C1-C10-alkyl, C3-C10-cycloalkyl or C6-C15-aryl, 
and where the radicals
R9 to R13 are hydrogen, C1-C10-alkyl, 5-7-membered cycloalkyl which can in turn carry a C1-C10-alkyl substituent, C6-C15-aryl or arylalkyl and where two adjacent radicals may if desired together be saturated or unsaturated cyclic groups having 4 to 15 carbons, or are Si(R14)3 where
R14 is C1-C10-alkyl, C6-C15-aryl or C3-C10-cycloalkyl,
or where the radicals R4 and Z together form a group xe2x80x94R15xe2x80x94Axe2x80x94 in which 
xe2x95x90BR16, xe2x95x90AlR16, xe2x80x94Gexe2x80x94, xe2x80x94Snxe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x95x90SO, xe2x95x90SO2, xe2x95x90NR16, xe2x95x90CO, xe2x95x90PR16 or xe2x95x90P(O)R16,
where
R16, R17 and R18 are the same or different and are hydrogen, halogen, C1-C10-alkyl, C1-C10-fluoroalkyl, C6-C10-fluoroaryl, C6-C10-aryl, C1-C10-alkoxy, C2-C10-alkenyl, C7-C40-arylalkyl, C8-C40-arylalkenyl or C7-C40-alkylaryl, or where two adjacent radicals in each case form a ring with the atoms linking them, and
M2 is silicon, germanium or tin, 
R19 is C1-C10-alkyl, C6-C15-aryl, C3-C10-cycloalkyl, alkylaryl or Si(R20)3,
R20 is hydrogen, C1-C10-alkyl, C6-C15-aryl which may in turn be substituted by C1-C4-alkyls, or is C3-C10-cycloalkyl
or where the radicals R4 and R12 together form a group xe2x80x94R15xe2x80x94.
Preference among the metallocene complexes of the formula I is given to 
The radicals X can be the same or different, but preferably are the same.
Of the compounds of the formula Ia, particular preference is given to those in which
M is titanium, zirconium or hafnium,
X is chlorine, C1-C4-alkyl or phenyl,
n is 2 and
R1 to R5 are hydrogen or C1-C4-alkyl.
Of the compounds of the formula Ib, preference is given to those in which
M is titanium, zirconium or hafnium,
X is chlorine, C1-C4-alkyl or phenyl,
n is 2,
R1 to R5 are hydrogen, C1-C4-alkyl or Si(R8)3, and
R9 to R13 are hydrogen, C1-C4-alkyl or Si(R14)3,
Particularly suitable compounds of formula Ib are those in which the cyclopentadienyl radicals are the same.
Examples of particularly suitable compounds include:
bis(cyclopentadienyl)zirconium dichloride, bis(pentamethylcyclopentadienyl)zirconium dichloride, bis(methylcyclopentadienyl)zirconium dichloride, bis(ethylcyclopentadienyl)zirconium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride and bis(trimethylsilylcyclopentadienyl)zirconium dichloride and the corresponding dimethylzirconium compounds.
Particularly suitable compounds of the formula Ic are those in which
R1 and R9 are the same and are hydrogen or C1-C10-alkyls,
R5 and R13 are the same and are hydrogen, methyl, ethyl, isopropyl or tert-butyl,
R2, R3, R10 and R11 are such that R3 and R11 are C1-C4-alkyl R2 and R10 are hydrogen or else two adjacent radicals R2 and R3 and also R10 and R11 are together cyclic groups having 4 to 12 carbons, 
M is titanium, zirconium or hafnium and
M2 is silicon
X is chlorine, C1-C4-alkyl or phenyl.
Examples of particularly suitable complex compounds Ic include:
Dimethylsilanediylbis(cyclopentadienyl)zirconium dichloride, dimethylsilanediylbis(indenyl)zirconium dichloride, dimethylsilanediylbis(tetrahydroindenyl)zirconium dichloride, ethylenebis(cyclopentadienyl)zirconium dichloride, ethylenebis(indenyl)zirconium dichloride, ethylenebis(tetrahydroindenyl)zirconium dichloride, tetramethylethylene-9-fluorenylcyclopentadienylzirconium diechloride, dimethylsilanediylbis(3-tert-butyl-5-methylcyclopentadienyl)-zirconium dichloride, dimethylsilanediylbis(3-tert-butyl-5-ethylcyclopentadienyl)-zirconium dichloride, dimethylsilanediylbis(2-methylindenyl)zirconium dichloride, dimethylsilanediylbis(2-isopropylindenyl)zirconium dichloride, dimethylsilanediylbis(2-tert-butylindenyl)zirconium dichloride, diethylsilanediylbis(2-methylindenyl)zirconium dibromide, dimethylsilanediylbis(3-methyl-5-methylcyclopentadienyl)-zirconium dichloride, dimethylsilanediylbis(3-ethyl-5-isopropylcyclopentadienyl)-zirconium dichloride, dimethylsilanediylbis (2-ethylindenyl)zirconium dichloride, dimethylsilanediylbis(2-methylbenzindenyl)zirconium dichloride dimethylsilanediylbis(2-ethylbenzindenyl)zirconium dichloride, ethylphenylsilanediylbis(2-ethylbenzindenyl)zirconium dichloride, ethylphenylsilanediylbis(2-methylbenzindenyl)zirconium dichloride, diphenylsilanediylbis(2-methylbenzindenyl)zirconium dichloride, diphenylsilanediylbis(2-ethylbenzindenyl)zirconium dichloride, and diphenylsilanediylbis(2-methylindenyl)hafnium dichloride and also the corresponding dimethylzirconium compounds.
Further examples of suitable complex compounds Ic include:
Dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride, dimethylsilanediylbis(2-methyl-4-[1-naphthylindenyl])zirconium dichloride, Dimethylsilanediylbis(2-methyl-4-isopropylindenyl)zirconium dichloride, Dimethylsilanediylbis(2-methyl-4,6-diisopropylindenyl)zirconium dichloride, dimethylsilanediylbis(2-ethyl-4-phenylindenyl)zirconium dichloride, Dimethylsilanediylbis(2-methyl-4-(para-4-butyl)phenylindenyl) zirconium dichloride, and also the corresponding dimethylzirconium compounds.
Particularly suitable compounds of the formula Id are those in which
M is titanium or zirconium
X is chlorine, C1-C4-alkyl or phenyl. 
and
R1 to R3 and R5 are hydrogen, C1-C10-alkyl, C3-C10-cycloalkyl, C6-C15-aryl or Si(R8)3 or where two adjacent radicals are cyclic groups having 4 to 12 carbons.
The synthesis of complex compounds of this kind can be carried out in accordance with methods known per se, preference being given to the reaction of the correspondingly substituted cyclic hydrocarbon anions with halides of titanium, zirconium, hafnium, vanadium, niobium or tantalum.
Examples of appropriate preparation techniques are described, inter alia, in Journal of Organometallic Chemistry, 369 (1989), 359-370.
It is also possible to employ mixtures of different metallocene complexes.
Component B) is aluminum trifluoride. This is a known compound which is described, for example, in Holleman-Wiberg, Lehrbuch d. Anorgan. Chemie, 101st Ed. 1995, p. 1073 ff, Walter de Gruyter (Berlin, N.Y.). It can be in either crystalline or, preferably, amorphous form. A very suitable process for preparing amorphous aluminum trifluoride is the reaction of aluminum triorganyls with, for example, boron trifluoride etherate, as described in R. Taube, Macromol. Chem. 194 (1993), 1273-1288. the aluminum trifluoride B) can be isolated preparatively or prepared in situ for use.
The molar ratio of aluminum trifluoride B) to metal complex A) is from 10,000:1 to 1:1, preferably from 100:1 to 1:1 and, with particular preference, from 50:1 to 1:1.
The cation-forming compound C) is generally a Lewis acid (electrically neutral or positively charged) or a Brxc3x6nsted acid. Suitable neutral Lewis acids are preferably those which form a non-nucleophilic anion after reaction with the transition metal component A). Suitable positively charged Lewis acids, and suitable Brxc3x6nsted acids, are preferably those having a conjugated anion with little or virtually no nucleophilicity.
One of the features of the invention is that both moderate and strong Lewis acids, and anions of little to virtually no nucleophilicity, can be used to generate a catalyst.
Suitable cation-forming compounds C) from the class of the moderate neutral and positively charged Lewis acids are compounds of elements of Groups 13 to 15 of the Periodic Table of the Elements, of the formula MetRxe2x80x2n, where Met is an element from groups 13 to 15 of the Periodic Table of the Elements, Rxe2x80x2 is inorganic or organic radicals which can be the same or different, and n is an integer from 3 to 5 and represents the valence of Met.
Preference is given in this context to compounds comprising elements of groups 13 and 15 with only halogen atoms as substituents. Particular preference is given to boron trifluoride and antimony pentafluoride.
Positively charged Lewis acids can be selected, for example, from compounds of the formulae [MetRxe2x80x2n+1]⊕[An]xe2x8ax96 or [MetRxe2x80x2nxe2x88x921]⊕[An]xe2x8ax96, where Met is an element from groups 13 to 16 of the Periodic Table of the Elements, Rxe2x80x2 is inorganic or organic radicals which can be the same or different, and n is an integer from 2 to 5 which represents the valence of Met. The nature of the corresponding anion [An]xe2x8ax96 is not critical per se, with anions such as boron tetrafluoride and antimony hexafluoride, for example, having proven suitable. Positively charged Lewis acids with exclusively organic substituents are preferred. Particular preference is given to compounds such as C(C6H5)3⊕BF4xe2x8ax96 or O(CH3)3⊕BF4xe2x8ax96, for example.
Suitable compounds from the class of the Brxc3x6nsted acids with an anion of low nucleophilicity (b) are those in which the anion is of the formula MetRxe2x80x2n+1xe2x8ax96 where Met is an element from groups 13 to 15 of the Periodic Table of the Elements, Rxe2x80x2 is inorganic or organic radicals which can be the same or different, and n is an integer from 3 to 5 and represents the valence of Met. Preference is given to anions carrying exclusively halogen substituents on the central element. Compounds such as HBF4 and HSbF6 are particularly preferred. These compounds can also be in the form of etherates.
A further class of anions of low nucleophilicity which can be used is derived from the formula Rxe2x80x2SO3⊕. In this formula Rxe2x80x2 is an inorganic or organic radical, preferably an organic C1-C10-alkyl or C6-C20-aryl radical, where preferably at least some of the hydrogen atoms can be substituted by halogen atoms, preferably by fluorine atoms. Examples of particularly preferred compounds of this class are acids Rxe2x80x2SO3-H, such as fluorosulfonic, phenylsulfonic, trifluoromethylsulfonic and pentafluorophenylsulfonic acid.
Strong, neutral Lewis acids as component C) are compounds of the formula (II)
M3X1X2X3xe2x80x83xe2x80x83II
where
M3 is an element from main group III of the Periodic Table, especially B, Al or Ga, preferably B,
X1, X2 and X3 are hydrogen, C1-C10-alkyl, C6-C15-aryl, alkylaryl, arylalkyl, haloalkyl or haloaryl each having 1 to 10 carbons in the alkyl radical and 6 to 20 carbons in the aryl radical, or are fluorine, chlorine, bromine or iodine, and in particular are haloaryls, preferably pentafluorophenyl.
Particular preference is given to compounds of the formula II in which X1, X2 and X3 are the same, preferably tris(pentafluorophenyl)borane.
Ionic compounds as component C), having strong Lewis-acid cations, are compounds of the formula III
[(Ya+)Q1Q2 . . . Qz]d+xe2x80x83xe2x80x83III
where
Y is an element of main groups I to VI or of subgroups I to VIII of the Periodic Table,
Q1 to Qz are radicals bearing a single negative charge, such as C1-C28-alkyl, C6-C15-aryl, alkylaryl, arylalkyl, haloalkyl, haloaryl each having 6 to 20 carbons in the aryl and 1 to 28 carbons in the alkyl radical, C3-C10-cycloalkyl, which can be unsubstituted or substituted by C1-C10-alkyl groups, or are halogen, C1-C28-alkoxy, C6-C15-aryloxy, silyl or mercaptyl,
a is an integer from 1 to 6 and
z is an integer from 0 to 5,
d being the difference a-z but being greater than or equal to 1.
Carbonium cations, oxonium cations and sulfonium cations, and also cationic transition metal complexes, are particular suitable. Mention may be made in particular of the triphenylmethyl cation, the silver cation and the 1,1xe2x80x2-dimethylferrocenyl cation. They preferably have noncoordinating counterions, especially boron compounds as are also mentioned in WO 91/09882, preferably tetrakis(pentafluorophenyl)borate.
Ionic compounds as component C) with Brxc3x6nsted acids as cations and preferably likewise noncoordinating counterions are mentioned in WO 91/09882; a preferred cation is N,N-dimethylanilinium.
The amount of metallocenium ion-forming compound is preferably from 0.1 to 10 equivalents based on the transition metal component A).
Component C) can also consist of or comprise an aluminoxane.
Compounds particularly suitable as the cation-forming component C) are open-chain or cyclic alumoxane compounds of the formula V or VI 
where R24 is a C1-C4-alkyl, preferably methyl or ethyl, and m is an integer from 5 to 30, preferably from 10 to 25.
These oligomeric alumoxane compounds are customarily prepared by reacting a solution of trialkylaluminum with water as is described, inter alia, in EP-A 284 708 and U.S. Pat. No. 4,794,096.
In general, the resulting oligomeric alumoxane compounds are in the form of mixtures of both linear and cyclic chain molecules of various length, so that m should be regarded as an average value. The alumoxane compounds can also be present in a mixture with other metal alkyls, preferably with aluminum alkyls.
As component C) it is additionally possible to employ aryloxyalumoxanes as described in U.S. Pat. No. 5,391,793, aminoaluminoxanes as described in U.S. Pat. No. 5,371,260, aminoaluminoxane hydrochlorides as described in EP-A 633 264, siloxyaluminoxanes as described in EP-A 621 279, or mixtures thereof.
It has been found advantageous to use the transition metal compound A) and the oligomeric alumoxane compound in amounts such that the atomic ratio between aluminum from the oligomeric alumoxane compound and the transition metal from the transition metal compound A is from 1:1 to 106:1, preferably from 1:1 to 104:1, and, in particular, from 1:1 to 10:1.
As component D), the catalyst system of the invention may also include, if desired, an organometallic compound, preferably a metal compound of the formula IV
M1(R21)r(R22)s(R23)txe2x80x83xe2x80x83IV
where
M1 is an alkali metal, an alkaline earth metal or a metal from main group III of the Periodic Table, i.e., boron, aluminum, gallium, indium or thallium,
R21 is hydrogen, C1-C10-alkyl, C6-C15-aryl, alkylaryl or arylalkyl having in each case 1 to 10 carbons in the alkyl radical and 6 to 20 carbons in the aryl radical,
R22 and R23 are hydrogen, halogen, C1-C10-alkyl, C6-C5-aryl, alkylaryl, arylalkyl or alkoxy having in each case 1 to 10 carbons in the alkyl radical and 6 to 20 carbons in the aryl radical,
r is an integer from 1 to 3
and
s and t are integers from 0 to 2, the sum r+s+t corresponding to the valence of M1.
Where component D) is present together with A) and/or C), it is not the same as components A) and, especially, C).
Among the metal compounds of formula IV preference is given to those in which
M1 is lithium, magnesium or aluminum and
R21 to R23 are C1-C10-alkyl.
Particularly preferred metal compounds of the formula IV are n-butyllithium, n-butyl-n-octylmagnesium, n-butyl-n-heptyl-magnesium, tri-n-hexylaluminum, tri-isobutylaluminum, triethylaluminum and trimethylaluminum.
If component D) is employed it is present in the catalyst system in an amount of preferably from 800:1 to 1:1, in particular from 500:1 to 50:1 (molar proportion of M1 from IV to transition metal M from I).
In addition to A), B), C) and, if used, D), the catalyst system may comprise a support substance.
Examples of suitable support substances are organic polymers, but preferably porous inorganic materials.
The support materials employed are preferably finely divided supports having a particle diameter in the range from 0.1 to 1000 xcexcn preferably from 10 to 300 xcexcm, and, in particular, from 30 to 70 xcexcm. Examples of suitable organic supports are finely divided polymers, such as finely divided polyethylene or polypropylene. Examples of suitable inorganic supports are aluminum trioxide, silicon dioxide, titanium dioxide or mixed oxides thereof, aluminum phosphate or magnesium chloride. It is preferred to employ silica gels of the formula SiO2.a Al2O3, in which a is a number from 0 to 2, preferably from 0 to 0.5. The support particles can be used in granular form and also spray-dried in microscopic form. Products of this kind are obtainable commercially, examples being Silica Gel 332 from Grace or ES 70xc3x97to from Crosfield.
Preferred inorganic support materials are acidic, inorganic metal oxides or semimetal oxides of very high porosity, which are described, for example, in the prior German Patent Application 197 20 980.7, especially on page 3, line 45 to page 5, line 11.
The support materials may have been pretreated thermally or chemically (with metal alkyl compounds, for example) in order to obtain a certain profile of properties of the support (for example, water content and/or hydroxyl content).
The catalyst system of the invention is generally obtained by reacting aluminum fluoride with a transition metal compound A) which has been brought into contact beforehand with a cation former C). This reaction can be conducted in homogeneous liquid phase or else in the presence of a support material, generally with the use of organic solvents as suspension media. The resulting compound can be employed as a catalyst directly, in suspension. An alternative possibility is to isolate the compound and to employ it per se as a catalyst in, for example, gas-phase processes; otherwise, it can be resuspended after isolation and then employed as a catalyst.
The aluminum fluoride B) can also be prepared in situ (for example, by reacting an aluminum alkyl compound with boron trifluoride) and then brought into contact, in the presence or absence of a support material, with the product of reaction of transition metal compound A) and cation former C). The reaction of the transition metal compound A) with the cation former C) can also be conducted in the presence of aluminum fluoride B) and in the presence or absence of a support material.
The catalyst system of the invention is employed to polymerize monomers having a Cxe2x80x94C double bond or a Cxe2x80x94C triple bond. Said Cxe2x80x94C double or Cxe2x80x94C triple bond, or both, can be arranged either at the ends of or within the module, either exocyclically or endocyclically. Preferred monomers with Cxe2x80x94C triple bond are C2-C10-alk-1-ynes, such as ethyne, propyne, 1-butyne, 1-hexyne, and also phenylacetylene. Preferred monomers with a Cxe2x80x94C double bond are C2-C20-alk-1-enes and C8-C20 vinylaromatic compounds. The polymerization process of the Invention is preferably employed to polymerize or copolymerize C2-C12-alk-1-enes. Preferred C2-C12-alk-1-enes are ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1heptene or 1-octene, and vinylaromatic monomers, such as styrene, p-methylstyrene or 2,4-dimethylstyrene, or mixtures of these C2-C12-alk-1-enes. Particular preference is given to homopolymers or copolymers of ethylene or of propylene, the proportion of ethylene or-propylene in the copolymers being at least 50 mol %. In the case of ethylene copolymers preference is given to those comprising propylene, 1-butene, 1-hexene, or 1-octene, or mixtures thereof, as further monomers. In the case of propylene copolymers, the copolymers concerned are in particular those comprising ethylene or 1-butene, or mixtures of these, as further monomers.
Preference is given to using the polymerization process of the invention to prepare polymers which comprise from 50 to 100 mol % of ethylene and from 0 to 50 mol %, in particular from 0 to 30 mol %, of C3-C12-alk-1-enes.
Preference is also given to those polymers which comprise from 50 to 100 mol % of propylene, from 0 to 50 mol %, in particular from 0 to 30 mol %, of ethylene and from 0 to 20 mol %, in particular from 0 to 10 mol %, of C4-C12-alk-1-enes.
The sum of the molar percentages is always 100.
The polymerization can be conducted by the techniques customary for polymerizing olefins, such as solution, suspension, stirred gas-phase or gas-phase fluidized-bed techniques, continuously or batchwise. As solvents or suspension media it is possible to use inert hydrocarbons, such as isobutane, or else the monomers themselves. Particularly suitable techniques for preparing the polymers are the suspension technique and the gas-phase technique (stirred gas phase, gas-phase fluidized bed).
Suitable reactors include continuously operated stirred vessels, loop reactors or fluidized-bed reactors, it also being possible if desired to use two or more reactors connected one after another in a row (reactor cascade).
The polymerization by means of the process of the invention is generally carried out at temperatures in the range from xe2x88x9250 to 300xc2x0 C., preferably from 0 to 150xc2x0 C., and under pressures of generally from 0.5 to 3000 bar, preferably from 1 to 80 bar. In the polymerization process of the invention it is advantageous to establish residence times of the respective reaction mixtures of from 0.5 to 5 hours, in particular from 0.7 to 3.5 hours. In the course of the polymerization it is also possible to use, inter alia, antistats and molecular mass regulators, an example being hydrogen.
Apart from for polymerization, the catalyst system of the invention can also be used for stoichiometric or catalytic, nonrepetitive carbon-carbon linkage, and for reducing carbonyl groups  greater than Cxe2x95x90O or imino groups  greater than Cxe2x95x90NH with carbon radicals, hydrides or amides, and also in the Diels-Alder reaction and in the hydrogenation of unsaturated carbon-carbon, carbon-heteroatom and heteroatom-heteroatom bonds with hydrogen and/or hydrides.
In general, these reactions proceed in the low molecular mass range and they generally lead to products having a molecular weight of less than about 1000.